EHB proportional solenoid valve with stepped gap armature

ABSTRACT

A control valve includes a magnetic pole member. An armature is slidably supported relative to the magnetic pole member for movement between a fully open position and a closed position. A biasing spring is disposed between the magnetic pole member and the armature for forcing the armature away from the magnetic pole member. A coil is placed about the magnetic pole member and the armature for inducing a magnetic field for moving the armature toward the magnetic pole member. One of either of the magnetic pole member or the armature has a recess for non-contactingly receiving the other when the armature moves between the fully open and closed positions. The control valve can be embodied as a normally open valve or a normally closed valve. The use of dual lateral poles and triple lateral poles create a flat magnetic force versus travel curve thereby allowing for greater proportional control of the valve. Additionally, the use of double lateral gaps and triple lateral gaps respectively results in force increases of 21% and 12% respectively. Compounding the force increases results in a net additional force of 36%.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/325,569 filed Sep. 28, 2001 and is a Continuation-In-Part of U.S.patent application Ser. No. 09/465,487, filed Dec. 16, 1999 nowabandoned, which in turn claims the benefit of U.S. ProvisionalApplication No. 60/112,431, filed on Dec. 16, 1998.

INCORPORATION BY REFERENCE

The disclosures of U.S. patent application Ser. No. 09/465,487 filedDec. 16, 1999 and U.S. Patent Application No. 60/112,431 filed Dec. 16,1998 are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates in general to vehicular brake systems, and inparticular to control valves for electronically controlled vehicularbrake systems.

Electronically controlled brake systems for vehicles are well known. Atypical electronically controlled brake system includes a hydrauliccontrol unit (HCU) connected in fluid communication between a mastercylinder and a plurality of wheel brake assemblies. The HCU includes ahousing containing control valves and other components such as a pumpfor selectively controlling pressure to the wheel brake assemblies.

The control valves are generally formed as electronically controlledsolenoid valves. A typical solenoid valve includes a cylindricalarmature slidably disposed in a tube or a sleeve for movement relativeto a valve body. The armature may be biased in a fully open or closedposition. The typical solenoid valve further includes a coil subassemblythat generates a magnetic flux for moving the armature from the biasedfully open position or closed position to a closed position or fullyopen position, respectively.

These types of control valves are generally used to control brake fluidpressure during non-base braking events, such as anti-lock, tractioncontrol, and vehicle stability control modes. However, because thesetypes of valves are designed to operate generally in only the fully openand closed positions they do not provide “proportional” controlcharacteristics desirable for controlling brake fluid pressure duringbase (“normal”) braking events. As such, these types of solenoid valvesare generally not well suited for applications in which the brake fluidpressure is electronically controlled during base braking events.

Other types of prior art valves, such as spool valves, have beenproposed which are capable of providing desirable proportional controlcharacteristics for electronically controlling brake fluid pressureduring base braking events. However, these types of valves arerelatively expensive.

Accordingly there is a need for a control valve used in electronicallycontrolled vehicular brake systems that is relatively inexpensive andprovides for proportional control of brake fluid pressure during basebraking events.

SUMMARY OF THE INVENTION

The invention relates to a control valve for vehicular brake systems.The control valve includes a magnetic pole member. An armature isslidably supported relative to the magnetic pole member for movementbetween a fully open position and a closed position. A biasing spring isdisposed between the magnetic pole member and the armature for forcingthe armature away from the magnetic pole member. A coil is placed aboutthe magnetic pole member and the armature for inducing a magnetic fieldfor moving the armature toward the magnetic pole member. One of eitherof the magnetic pole member or the armature has a recess fornon-contactingly receiving the other when the armature moves between thefully open and closed positions. The control valve can be embodied as anormally open valve or a normally closed valve.

Various objects and advantages of this invention will become apparent tothose skilled in the art from the following detailed description of thepreferred embodiments, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a vehicular brake system including ahydraulic control unit having control valves according to thisinvention.

FIG. 2 is a sectional view of a normally open control valve according tothe present invention illustrated in an energized closed position.

FIG. 3 is a sectional view of a normally closed control valve accordingto the present invention illustrated in a non-energized closed position.

FIG. 4 is a sectional view of a second embodiment of a normally opencontrol valve according to this invention illustrated in an energizedclosed position.

FIG. 5 is a sectional view of a second embodiment of a normally closedcontrol valve according to the present invention illustrated in anon-energized closed position.

FIG. 6 is a sectional view of a third embodiment of a normally closedcontrol valve according to the present invention illustrated in anon-energized closed position.

FIG. 7 is an enlarged portion of the control valve of FIG. 6 bounded bythe circle A.

FIG. 8 is a sectional view of a normally open control valve according tothe present invention illustrated in an energized closed position.

FIG. 9 is a sectional view of a normally open proportional valveaccording to the present invention illustrated in an non-energized openposition.

FIG. 10 is an enlarged portion of the proportional valve of FIG. 9bounded by the circle labeled FIG. 10.

FIG. 10A is a view similar to FIG. 10, except with the armature and polemember positioned to more clearly depict an axial flux gap.

FIG. 11 is a view similar to FIG. 10, except with the valve illustratedin a energized closed position.

FIG. 12 is a sectional view of a normally open proportional valveaccording to the present invention illustrated in an non-energizedposition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A vehicular brake system is shown generally at 10 in FIG. 1. The brakesystem 10 includes a hydraulic control unit (HCU), indicated generallyat 12, connected in fluid communication with a fluid supply source 14and a plurality of wheel brake assemblies indicated generally at 16(only one shown). A first pressure sensor 17 is connected in fluidcommunication with each of the wheel brakes. The wheel brake assembly 16is shown as a disc brake 16. Alternatively, the wheel brake assembly 16may be a drum brake or any other known vehicular wheel brake assembly.

The HCU 12 includes a housing 18 containing a plurality of brakecircuits 20. Each brake circuit 20 includes a set of components forcontrolling the brake pressure of at least one of the wheel brakeassemblies 16. For purposes of clarity of illustration, only one brakecircuit 20 is illustrated.

The brake circuit 20, as shown, includes a pump 22 having a pump inlet24 and a pump outlet 26. The pump inlet 24 is connected in fluidcommunication with the fluid supply source 14. The pump outlet 26 isconnected in fluid communication with a second pressure sensor 27, anaccumulator 28 and an inlet 30 of a cutoff valve 32. The accumulator 28is also connected in fluid communication with the inlet 30 of the cutoffvalve 32. An outlet 34 of the cutoff valve 32 is connected in fluidcommunication with an inlet 36 of an isolation valve 38. An outlet 40 ofthe isolation valve 38 is connected in fluid communication with thewheel brake assembly 16 and an inlet 42 of a dump valve 44. The inlet 42of the dump valve 44 is also connected in fluid communication with thewheel brake assembly 16. An outlet 46 of the dump valve 44 is connectedin fluid communication with the fluid supply source 14.

The pump 20 and accumulator 28 are of well-known types. Preferably, thecutoff valve 32 is a bi-positionable control valve movable betweenopened and closed positions. Preferably, the isolation valve 38 and thedump valve 44 are embodied as normally closed and normally open controlvalves, respectively. Alternatively, the isolation valve 38 may beembodied as a normally open control valve and/or the dump valve 44 maybe embodied as a normally closed control valve.

It is understood that for other vehicular brake systems the HCU 12 mayinclude additional, less or differing components. Such components may beplaced in different fluid communication arrangements depending on thespecified performance requirements and/or functions provided by thedesignated vehicular brake system.

FIG. 2 illustrates the structure of a normally open control valve 48according to this invention. The control valve 48 may be employed as theisolation valve 38 and/or the dump valve 44 schematically shown inFIG. 1. The control valve 48 includes a magnetic pole member orcylindrical valve body 50 having a first end 52 and a second end 54. Thevalve body 50 is fixedly disposed in the housing 18 with a portion ofthe valve body 50 adjacent to the second end 54 extending from thehousing 18. An inlet fluid passage 56 extends from the first end 52 tothe second end 54 through a central portion of the valve body 50. Theopening of the inlet fluid passage 56 at the first end 52 aligns with aconduit 58 formed in the housing 18. When the control valve 48 isemployed as the isolation valve 38, the conduit 58 is adapted forplacement in fluid communication with the outlet 34 of the cutoff valve32. When employing the control valve 48 as the dump valve 44, theconduit 58 is adapted for placement in fluid communication with theoutlet 40 of the isolation valve 38 and the wheel brake assembly 16. Afilter assembly 60 is pressed into the opening at the first end 52 forfiltering particulate from the fluid entering the control valve 48. Thefilter assembly 60 is optional.

A portion of the inlet fluid passage 56 extending inwardly from thesecond end 54 of the valve body 50 forms a valve seat 62. Preferably,the valve seat 62 is conical. Alternatively, the valve seat 62 may be ofany suitable shape. A portion of the valve body 50 directly adjacent tothe second end 54 tapers outwardly from the second end 54 forming afrustum 63. As described below, the frustum 63 forms an extendingportion of the valve body 50. A plurality of outlet fluid passages 64extend from an outer surface of the frustum 63 to an annular recess 65formed in the valve body 50. The annular recess 65 aligns with a conduit66 formed in the housing 18. When the control valve 48 is employed asthe isolation valve 38, the conduit 66 is adapted for placement in fluidcommunication with the wheel brake assembly 16 and the inlet 42 of thedump valve 44. When employing the control valve 48 as the dump valve 44,the conduit 66 is adapted for placement in fluid communication with thefluid supply source 14.

A first annular groove 68 is formed in the valve body 50 between thefirst end 52 and the annular recess 65. A first seal 70 is disposed inthe first groove 68 for preventing fluid from flowing outside the valvebody 50 between the first end 52 and the annular recess 65. A secondannular groove 72 is formed in the valve body 50 between the second end54 and the annular recess 65. A second seal 74 is disposed in the secondgroove 72 for preventing fluid from the annular recess 65 from escapingthe housing 18. The first and second seals 70, 74 may be of any suitabletype, such as O-rings.

The control valve 48 further includes an armature 76 slidably disposedin a sleeve 78 for movement between a fully open position and a closedposition. The sleeve 78 has an open end and a closed end 80. The openend of the sleeve 78 receives a portion of the valve body 50 adjacent tothe second end 54. The sleeve 78 is secured to a stepped portion 82 ofthe valve body 50. Preferably, the sleeve 78 is laser welded to thestepped portion 82 so as to provide a fluid tight seal between thesleeve 78 and valve body 50.

An conical shaped recess 84 complementary to the frustum 63 is formed atthe end of the armature 76 adjacent to the frustum 63 for receiving thefrustum 63 when the armature 76 moves from the fully open position tothe closed position. An axial bore 86 aligning with the inlet fluidpassage 56 is formed in the armature 76. A valve ball 88 is pressed intothe bore 86 with a portion of the valve ball 88 extending from the bore86. The valve ball 88 engages the valve seat 62 when the armature 76 isin the closed position as illustrated in FIG. 2, such that a gap ismaintained between the frustum 63 and the recess 84. The valve ball 88is substantially non-deformable and sized to block fluid from flowingfrom the inlet fluid passage 56 to the outlet fluid passages 64 when inthe closed position. The valve ball 88 is preferably non-magnetic, butmay be magnetic.

As shown, the opening of the bore 86 is flush with the base of therecess 84. Alternatively, the material surrounding the opening of thebore 86 may extend outwardly away from the base of the recess 84 for thepurpose of increasing the gap or distance between the frustum 63 and therecess 84 at the closed position.

A biasing spring 90 is placed about the valve body 50 between thestepped portion 82 and the frustum 63. One end of the biasing spring 90engages an inner collar of the stepped portion 82 and the other end ofthe biasing spring 90 engages an end of the armature 76 adjacent to thevalve body 50. The biasing spring 90 resiliently biases the armature 76in the fully open position such that the valve ball 88 is fully spacedfrom the valve seat 62.

Axial troughs 92 are formed along the perimeter of the armature 76 forproviding a fluid passageway between the ends of the armature 76. Thetroughs 92 prevent a fluid lock-up condition inhibiting the rapiddisplacement of the armature 76 relative to the valve body 50.

The control valve 48 further includes a solenoid subassembly, indicatedgenerally at 94. The solenoid subassembly 94 includes a cylindricalcasing 96 having an open end and a partially enclosed end 98 thatincludes a turned-in flange 100. A coil 102 is disposed within thecasing 96. The coil 102 is shown wound upon a bobbin 104, but may beused without the bobbin 104. When energized, the coil 102 induces amagnetic flux between the armature 76 and the valve body 50 for movingthe armature 76 from the fully open position to the closed position. Aflux ring 106 is pressed into the casing 96 adjacent to the open end ofthe casing 96 for securing the bobbin 104. Winding terminals 108 a and108 b extend outwardly through respective openings formed in thepartially enclosed end 98. The terminals 108 a, 108 b are adapted forconnection to an electronic module (not shown) of a well-known type.

The solenoid subassembly 94 is placed about the sleeve 78 and a portionof the valve body 50 extending from the housing 18. The solenoidsubassembly 94 is held in place by any desired means, such as by amodule cap (not shown) of a well-known type.

FIG. 3 illustrates the structure of a normally closed control valve 109according to this invention. As mentioned above, the control valve 109may be employed as the isolation valve 38 and/or the dump valve 44schematically shown in FIG. 1. The control valve 109 includes agenerally cylindrical valve body 110 having a first end 112 and a secondend 114. The valve body 110 is fixedly disposed in the housing 18 with aportion adjacent to second end 114 extending from the housing 18. Aninlet fluid passage 115 extends between the ends 112, 114 through acentral portion of the valve body 110. The opening of the inlet fluidpassage 115 at the first end 112 aligns with a conduit 116 formed in thehousing 18. When the control valve 109 is employed as the isolationvalve 38, the conduit 116 is adapted for placement in fluidcommunication with the outlet 34 of the cutoff valve 32. When employingthe control valve 109 as the dump valve 44, the conduit 116 is adaptedfor placement in fluid communication with the outlet 40 of the isolationvalve 38 and the wheel brake assembly 16. An optional filter assembly(not shown), such as the filter assembly 60 shown in FIG. 2, may bepressed into the opening at the first end 112. The opening of the inletfluid passage 115 at the second end 114 forms a valve seat 117.Preferably, the valve seat 117 is conical. Alternatively, the valve seat117 may be of any suitable shape.

A plurality of outlet fluid passages 118 are formed in the valve body100. Each outlet fluid passages 118 includes an opening at the secondend 114 and an opening adjoining an annular chamber 119 formed betweenthe first and second ends 112, 114, which is bounded by the outersurface of the valve body 110 and a counterbore formed in the housing18. A conduit 120 formed in the housing 18 is placed in fluidcommunication with the chamber 119. When the control valve 109 isemployed as the isolation valve 38, the conduit 120 is adapted forplacement in fluid communication with the wheel brake assembly 16 andthe inlet 42 of the dump valve 44. When employing the control valve 109as the dump valve 44, the conduit 120 is adapted for placement in fluidcommunication with the fluid supply source 14.

An annular groove 122 is formed in the valve body 110 between the firstend 112 and the chamber 119. A first seal 124 of any suitable type isdisposed in the first groove 122 for preventing fluid from flowingoutside the valve body 110 between the first end 112 and the chamber119. The valve body 110 further includes an annular flange 123 adjacentto the second end 114. The annular flange 123 is sealably secured withina counterbore formed in the housing 18.

The control valve 109 further includes an armature 128 having a firstend 130 and a second end 132 slidably disposed in a tube 134 formovement between a closed position and a fully open position. The tube134 receives a portion of the valve body 110 such that the second end114 of the valve body 110 is adjacent to the first end 130 of thearmature 128. The tube 134 is preferably laser welded to the valve body110 so as to provide a fluid tight seal.

An axial bore 136 aligning with the inlet fluid passage 115 is formed inthe first end 130 of the armature 128. A valve ball 138 is pressed intothe bore 136 with a portion of the valve ball 138 extending from thebore 136. The valve ball 138 engages the valve seat 117 when thearmature 128 is in the closed position as illustrated in FIG. 3, suchthat a gap is maintained between the armature 128 and the openings ofthe outlet fluid passages 118 at the second end 114. The valve ball 138is substantially non-deformable and sized to block fluid from flowingfrom the outlet fluid passages 118 to the inlet fluid passage 115 whenin the closed position. A cylindrically shaped recess 140 is formed inthe second end 132 of the armature 128.

The control valve 109 further includes a magnetic pole member orcylindrical core element 142 extending from and sealably secured to thetube 134 adjacent to the second end 132 of the armature 128. The coreelement 142 has an inwardly stepped portion 144 complementary to therecess 140. The recess 140 receives the stepped portion 144 when thearmature 128 moves from the closed position to the fully open position.A biasing spring 146 is placed about the stepped portion 144 and engagesthe corresponding ends of the armature 128 and core element 142. Thebiasing spring 146 resiliently biases the armature 128 in the closedposition such that the valve ball 138 is firmly seated in the valve seat117, thereby preventing fluid from flowing from the inlet fluid passage115 to the outlet fluid passages 118. Alternatively, the biasing spring146 may be replaced by a spring (not shown) disposed in an axial bore(not shown) formed in either the core element 142 or the armature 128.

Axial troughs 148 are formed along the perimeter of the armature 128 forproviding a fluid passageway between the ends 130, 132 of the armature128. The troughs 148 prevent a fluid lock-up condition inhibiting therapid displacement of the armature 128.

The control valve 109 further includes a solenoid subassembly indicatedgenerally at 150. The solenoid subassembly 150 includes a cylindricalcasing 152 that is open at one end and having a turned-in flange 154 atthe other end. A coil 156 is disposed in the casing 152. The coil 156 isshown wound upon a bobbin 157, but may used without the bobbin 157. Whenenergized, the coil 156 induces a magnetic field between the armature128 and the core element 142 for moving the armature 128 from the closedposition to the fully open position. A flux ring 158 is pressed into thecasing 152 adjacent to open end of the casing 152 for securing thebobbin 158. Winding terminals 160 a and 160 b extend outwardly throughrespective openings adjacent to the flange 154. The terminals 160 a, 160b are adapted for connection to the electronic module.

The solenoid subassembly 150 is placed about the tube 134 and theportion of the core element 142 extending from the tube 134. Thesubassembly 150 is held in place by any desired known means.

In operation, the electronic controller commands the pump 22 to cyclewhen the fluid pressure in the accumulator 28 falls below apredetermined working pressure. The pump 22 in turn transfers fluid fromthe fluid supply source 14 to the accumulator 28. The electroniccontroller commands the pump 22 to cease cycling when the accumulator 28is fully charged.

In addition, the electronic controller commands the cutoff valve 32 toopen and close for controlling fluid flow to the isolation valve 38.During non-braking events the cutoff valve 32 is closed, whereas duringbraking events the cutoff valve 32 is opened.

Additionally, the electronic controller, acting upon input signalsreceived from the pressure sensors 17, 27 and various other controlsensors (not shown) of well-known types, selectively energizes andde-energizes the isolation valve 30 and the dump valve 44 duringdesignated braking events.

In employing the normally open control valve 48 as the isolation valve30 or the dump valve 44, the electronic controller, when energizing thecontrol valve 48, controls the amount of current supplied to the coil102 for the purpose of controlling the fluid pressure of the wheel brakeassembly 16. Having been supplied with a given current, the coil 102induces a given magnetic flux between the magnetic pole member or valvebody 50 and the armature 76. The given magnetic flux in turn generates agiven magnetic force on the armature 76 that acts to move the armature76 from the fully open position toward the closed position. In additionto being dependent on the amount of current supplied to the coil 102,the magnetic force acting on the armature 76 is dependent on thedistance between the frustum 63 and the recess 84. In moving from thefully open position to the closed position, the armature 76 worksagainst the biasing spring 90 and the increasing pressure of fluidbetween the armature 76 and the valve body 50. Accordingly, the amountof movement of the armature 76 is a function of the magnetic forceacting on the armature 76, the spring rate of the biasing spring 90 andthe fluid pressure between the armature 76 and the valve body 50.

As the armature 76 moves toward the closed position, the valve ball 88advances toward the valve seat 62, which in turn causes the flow ratefrom the inlet fluid passage 56 to the outlet fluid passages 64 tosteadily decrease. When the armature 76 is positioned in the closedposition, the valve ball 88 engages the valve seat 62, thereby blockingthe flow of fluid from the inlet fluid passage 56 to the outlet fluidpassages 64. When the normally open valve 48 is de-energized, thebiasing spring 90 forces the armature 76 to return to the fully openedposition.

In employing the normally closed control valve 109 as the isolationvalve 30 or the dump valve 44, the electronic controller, whenenergizing the control valve 109, controls the amount of currentsupplied to the coil 156 for the purpose of controlling the fluidpressure of the wheel brake assembly 16. Having been supplied with agiven current, the coil 156 induces a given magnetic flux between themagnetic pole member or core element 142 and the armature 128. The givenmagnetic flux in turn generates a given magnetic force on the armature128 that acts to move the armature 128 from the closed position towardthe fully open position. In addition to being dependent on the amount ofcurrent supplied to the coil 156, the magnetic force acting on thearmature 128 is dependent on the distance between the stepped portion144 and the recess 140. In moving from the closed position to the fullyopen position, the armature 128 works against the biasing spring 146 andthe decreasing pressure of the fluid between the armature 128 and thevalve body 110. Accordingly, the amount of movement of the armature 128is a function of the magnetic force acting on the armature 128, thespring rate of the biasing spring 146 and the fluid pressure between thearmature 128 and the valve body 110.

As the armature 128 moves toward the fully open position, the valve ball138 retreats from the valve seat 117, which in turn causes the flow ratefrom the inlet passage 115 to the outlet flow passages 118 to steadilyincrease. When the normally closed control valve 36 is de-energized, thebiasing spring 156 forces the armature 128 to return to the closedposition.

When the isolation valve 38 is open, pressurized fluid is transferredfrom the accumulator 28 to the wheel brake assembly 16 through the inletfluid passage 56 and the outlet fluid passages 64. When the dump valve44 is open, fluid is transferred from the wheel brake assembly 16 to thefluid supply source 14 through the inlet fluid passage 115 and theoutlet passages 118.

In the embodiment shown in FIG. 2, the recess 84 of the armature 76receives the frustum 63 of the valve body 50. Alternatively, theorientation of the frustum 63 and the recess 84 may be reversed.Specifically, FIG. 4 shows a normally open control valve 48′ including avalve body 50′ having a recess 84′ formed at one end. The control valve48′ further includes an armature 76′ having a frustum 63′ formed at anend adjacent to the recess 84′. As with the control valve 48 shown inFIG. 2, the frustum 63′ is complementary of the recess 84′.

Similarly, with respect to the normally closed valve 109, the male andfemale orientation of the corresponding ends of the armature 128 and thecore element 142 may be reversed.

In addition, while the corresponding or mating ends of the valve bodies50 and 50′ and the armatures 76 and 76′ are shown as complementary coneshapes, the mating ends may be any desired shape such as cylindrical,square or the like. Moreover, while it is preferable the mating ends becomplementary they need not be. Likewise, the mating ends of thearmature 128 and the core element 142 may be any desired shapes whethercomplementary or not.

An important feature is that the armature 76, 76′, 128 and correspondingmagnetic pole member 50, 50′, 142 are receivable in one or the other.The purpose of such constructions is to provide an overlappingarrangement between the armature 76, 76′, 128 and corresponding magneticpole member 50, 50′, 142 as the armature 76, 76′, 128 moves between theopen and closed positions. This overlapping arrangement in turn providesfor a more gradual change in the magnetic force acting upon the armature76, 76′, 128 as the armature 76, 76′, 128 is displaced relative to thecorresponding magnetic pole member 50, 50′, 142 when compared to a valvestructure absent the overlapping arrangement. A flatter magnetic forceversus displacement curve provides for smoother controlled movement ofthe armature 76, 76′, 128, thereby reducing the noise and vibrationlevels of the isolation valve 38, 38′ and dump valve 44 as compared toconventional isolation and dump valves.

A second embodiment of a normally closed control valve is indicatedgenerally at 200 in FIG. 5. The control valve 200 can be used as theisolation valve 38 and/or the dump valve 44 in the brake system 10 ofFIG. 1. The control valve 200 includes a seat or valve body 202 mountedin the housing 18. An adapter 204 has a lower annular flange 206 that iscrimped onto the seat 202 to retain the adapter 204 thereto. An annularfilter assembly 208 is fitted about the adapter 204 and seat 202.

An armature 210 is slidably disposed in a tube or sleeve 212. A ball 213is pressed into an axial bore 214 formed in the armature 210. A crosshole 216 is formed in the armature 210 in fluid communication with theaxial bore 214. A first end of a spring 218 engages an insert 220disposed in a cavity in the armature 210. A second end of the spring 218is fitted about an extension 222 formed on a magnetic pole member 224. Asolenoid subassembly 226 is fitted over the pole member 224 and sleeve212. Upon energization, the solenoid subassembly 226 produces anelectromagnetic force that urges the armature 210 against the spring 218toward the pole member 224 to open the control valve 200.

The pole member 224 has an inwardly stepped portion 228 complementary toa recess 230 formed in the armature 212. The recess 230 receives thestepped portion 228 when the armature 212 moves from a closed positionto an open position. The magnetic force acting on the armature 212 isdependent upon current supplied to the solenoid subassembly 226 and thedistance between the stepped portion 228 and the recess 230.

A third embodiment of a normally closed control valve is indicatedgenerally at 300 in FIG. 6. The control valve 300 can be used as theisolation valve 38 and/or the dump valve 44 in the brake system 10 ofFIG. 1. The control valve 300 includes a seat or valve body 302 mountedin the housing 18. An adapter 304 has a lower annular flange 306 that iscrimped onto the seat 302 to retain the adapter 304 thereto. An annularfilter assembly (not illustrated) can be fitted about the adapter 304and seat 302.

An armature 310 is slidably disposed in a tube or sleeve 312. A ball 313is pressed into an axial bore 314 formed in the armature 310. A crosshole 316 is formed in the armature 310 in fluid communication with theaxial bore 314. A first end of a spring 318 engages the armature 310. Asecond end of the spring 318 is fitted about an extension 322 formed ona magnetic pole member 324. A solenoid subassembly 326 is fitted overthe pole member 324 and sleeve 312. Upon energization, the solenoidsubassembly 326 produces an electromagnetic force that urges thearmature 310 against the spring 318 toward the pole member 324 to openthe control valve 300.

The pole member 324 has a series of inwardly stepped portions. In theembodiment of FIG. 6, a first stepped portion 325 and a second steppedportion 326 are shown. A recess 330 is formed in the armature 310. Therecess 330 is complementary to and receives the stepped portions 325 and326 when the armature 310 moves from a closed position to an openposition. Preferably, the recess 330 includes a first stepped portion332 and a second stepped portion 334. This “double step” formed betweenthe pole member 324 and the armature 310 increases the air gap area inthe control valve 300 so that its output force is increased withoutincreasing the size of the control valve 300. The increased axial forceprovided by this construction can permit the size of a control valve 300to be reduced and still provide a desired output force.

Proportional solenoids with cylindrical lateral magnetic gaps can bedesigned to have magnetic output forces that are reasonably constantover their operating travel range. This allows stable operation andminimized the effects of axial tolerances of the parts. The permeanceand axial force of this type of lateral magnetic gap are described bythe following equations: $\begin{matrix}{P = \frac{\mu\; S}{g}} & (1) \\{F_{axial} = {\frac{1}{2}({NI})^{2}\frac{\partial P}{\partial x}}} & (2) \\{{{F_{axial} = {\frac{1}{2}\frac{\mu}{g}({NI})^{2}\frac{\partial S}{\partial x}}}P = {{permeance}\mspace{14mu}{of}\mspace{14mu}{lateral}\mspace{14mu}{gap}}}{\mu = {{permeability}\mspace{14mu}{of}\mspace{14mu}{medium}\mspace{14mu}{in}\mspace{14mu}{gap}}}{S = {{flux}\mspace{14mu}{area}}}{g = {{lateral}\mspace{14mu}{clearance}\mspace{14mu}{gap}}}{F_{axial} = {{axial}\mspace{14mu}{force}\mspace{14mu}{due}\mspace{14mu}{to}\mspace{14mu}{radial}\mspace{14mu}{gap}}}{{{NI} = {{magnetomotive}\mspace{14mu}{force}}}x = {{travel}\mspace{14mu}{of}\mspace{14mu}{armature}\mspace{14mu}{relative}\mspace{14mu}{to}\mspace{14mu}{stationary}\mspace{14mu}{pole}\mspace{14mu}{member}}}} & (3)\end{matrix}$To increase the output force of these solenoids or to decrease theircurrent draw or power consumption, it usually is necessary to increasethe diameter of the armature and thus the outer diameter of thesolenoid. Generally, this is an unacceptable adjustment to the size ofthe solenoid. The dual stepped radial air gaps increase the air gap areaand the a ∂S/∂x term in the axial force equation. This allows the outputforce of the solenoid to be significantly increased without increasingthe size of the solenoid. Alternatively, the outer diameter of thesolenoid could be decreased or the current draw or power consumptionreduced. In one demonstrative case, a flat force versus travel curve fora proportional control valve with dual lateral pole showed an increaseof twenty-one percent (21%) of output force compared to a valve with asingle pole.

A third embodiment of a normally open control valve is indicatedgenerally at 400 in FIG. 8. The control valve 400 can be used as theisolation valve 38 and/or the dump valve 44 in the brake system 10 ofFIG. 1. The control valve 400 includes a seat or valve body 402 mountedin the housing 18. An adapter 404 has a lower annular recess 406 thatreceives the seat 402 to retain the adapter 404 thereto. An annularfilter (not illustrated) can be fitted about or into the seat 402.

A pin 410 is slidably disposed in a bore 412 formed in the adapter 404.A first ball 412 is pressed into a cavity 414 formed in a first end ofthe pin 410. A second ball 413 is pressed into a cavity 415 formed in asecond end of the pin 410. A cross hole 416 is formed in the seat 402 influid communication with an axial bore 417 of the seat 402. A first endof a spring 418 engages the adapter 404. A second end of the spring 418engages a stop 419 mounted on the pin 410.

An armature 424 is received in a closed tube 425 that is attached to theadapter 404. A solenoid subassembly 426 is fitted over the tube 425.Upon energization, the solenoid subassembly 426 produces anelectromagnetic force that urges the armature 410 against the spring 418toward the adapter 404 to close the control valve 400.

The adapter 404 has a series of inwardly stepped portions. In theembodiment of FIG. 8, a first stepped portion 428 and a second steppedportion 429 are shown. A recess 430 is formed in the armature 424. Therecess 430 is complementary to and receives the stepped portions 428 and429 when the armature 424 moves from an open position to a closedposition. Preferably, the recess 430 includes a first stepped portion432 and a second stepped portion 434. This “double step” formed betweenthe adapter 404 and the armature 424 increases the air gap area in thecontrol valve 400 so that its output force is increased withoutincreasing the size of the control valve 400. The increased axial forceprovided by this construction can permit the size of a control valve 400to be reduced and still provide a desired output force.

A fourth embodiment of a normally open control valve is indicatedgenerally at 500 in FIG. 9. The control valve 500 can also be used asthe dump valve 44 in the brake system 10 of FIG. 1, as described below.The control valve 500 includes a seat or valve body 502 mounted in thehousing 18.

A cross hole 516 is formed in the seat 502 in fluid communication withan axial bore 517 of the seat 502. An adapter 504 has a lower annularrecess 506 that receives the seat 502 to retain the adapter 504 thereto.An inlet filter and an outlet annular filter are fitted about or intothe seat 502. A bore 512 is formed through the adapter 504. A pin 510 isslidably disposed in the bore 512. A first ball 511 is pressed into acavity 514 formed in a first end of the pin 510. A second ball 513 ispressed into a cavity 515 formed in the valve armature and connected toa second end of the pin 510. A first end of a spring 518 engages theseat 502. A second end of the spring 518 engages a stop 519 mounted onthe pin 510.

An armature 524 is received is a closed tube 525 that is attached to theadapter 504. A solenoid subassembly 526 is fitted over the tube 525.Upon energization, the solenoid subassembly 526 produces anelectromagnetic force that urges the armature 524 towards the adapter504. Moving the armature 524 towards the adapter 504 also urges the pin510 toward the valve seat 502, so that the ball 511 engages the seat toclose the control valve 500. The movement of the pin 510 towards thevalve seat 502 compresses the spring 518.

The adapter 504 has a series of inwardly stepped portions. In theembodiment of FIG. 9, and as more clearly seen in an enlarged portionshown in FIGS. 10 and 11, a first stepped portion 528 and a secondstepped portion 529 are shown. A stepped recess 530 is formed in thearmature 524. The recess 530 is substantially complementary to andgenerally receives the stepped portions 528 and 529 when the armature524 moves from an open position to a closed position, as shown in FIG.11, described below. However, due to manufacturing tolerances and otherfactors, it is not required that the armature 524 and adapter 504 matcheach other perfectly. Preferably, the recess 530 includes a firststepped portion 532 and a second stepped portion 534. This “double step”formed between the adapter 504 and the armature 524 increases the airgap area in the control valve 500 so that its output force is increasedwithout increasing the size of the control valve 500. Specifically, afirst air gap or flux gap 530 a is defined between the step 532 of thearmature 524 and the step 528 of the adapter 504, and a second flux gap532 a between the step 534 of the armature 524 and the step 529 of theadapter 504. The increased axial force provided by this construction canpermit the size of the control valve 500 to be reduced and still providea desired output force. This effect is preferably enhanced by a thirdflux gap 530 b and is defined between the step 530 of the valve armature524 and the flux ring or pole 501. The third gap herein is termed alateral gap. This “triple gap” system as a whole works to increase theoverall force that is operating on the valve armature 524 whilemaintaining a relatively linear force versus displacement operatingcurve for the control valve system.

Additionally, the third gap 530 b can have an axial component, as shownin FIG. 10A. As shown in FIG. 10A, flux ring 501 is positioned at alateral and axial distance from the armature 524. The valve 500 in FIG.10A is shown in an open position with the third flux gap 530 brepresented by the space between the end of the armature 524 and the topof the pole 501. This third flux gap 530 b can be termed an axial gap.The double gap portion remains as defined between the steps 528, 529 ofthe adapter 504 and the steps 530, 532 of the armature 524. The armature524 is preferably positioned axially distant from the pole 501 so thataxial forces due to the axial flux gap are relatively small relative tothe axial force due to the lateral gaps.

The armature 524 has been shown having a generally concave shape withthe armature 524 recessed to fit over the pole piece. In an alternateembodiment the adapter can be recessed such that it can receive thearmature. In either embodiment, the magnetic effect desired by the fluxgap design is not changed by the use of a recessed armature or arecessed adapter.

Previously, a proportional solenoid valve with a high output steppedarmature was proposed and disclosed and has been implemented. The dualstepped radial air gap increased the air gap area and the ∂S/∂x term inthe axial force equation. This allowed the output force of the solenoidto be significantly increased without increasing the size of thesolenoid. In this proposed new design, the flux ring tube section wasextended upwards to form an external third lateral gap. This thirdlateral gap adds another ∂S/∂x term to the axial force equation, therebyfurther increasing the axial output force without increasing the size ofthe solenoid. This concept has been described with respect to a normallyopen proportional solenoid valve however this design can similarly beadapted to a normally closed proportional solenoid valve. The use ofthis design concept creates a low cost or no cost method to furtherincrease EHB output force or decrease current consumption and heatingwithout changing solenoid size. Additionally, a flat force versus travelcurve for a proportional control valve with triple lateral pole showedan increase of twelve percent (12%) of output force compared to a valvewith a dual pole. Compounding this increase in force with the increaseon force by using a double pole results in a total increase in force ofoutput force of thirty-six percent (36%) over the output force of asingle pole.

Shown in FIG. 11 is an enlarged portion of the embodiment of FIG. 9. InFIG. 11, the gap 530 between the adapter steps 528, 529 and the armaturesteps 532, 534 is reduced in that the normally open proportional valveis in an energized and closed position. In this position, the steppedportions 532, 534 of the armature 524 are moved closer to the generallycomplementary stepped portions 528 and 529 of the adapter 504, therebyreducing the gap 530.

In the embodiment shown in FIG. 9, the ball 511 is sized relative to thebore 512 so that the ball 511 is small enough to effectively self-centerand thus seal in the bore in the valve seat 502. This helps ensure thatthe ball 511 is maintained in position over the valve opening despitehydraulic flow variation around the surface of the ball 511. While thelateral movement of the pin should be minimal using appropriatemanufacturing tolerances, the design of this embodiment will allowprompt re-sealing of the ball 511 onto the bore in the valve seat 502.When the solenoid subassembly 526 is energized, the spring 518 willexert a sufficient force that the ball 511 to seal against the seat 502against a maximum design pressure.

The shape of the seat 502, is preferably conical, and can minimize theflow forces on the portion that contacts the seat 502. The seatingsurface of the valve seat 502, is raised and is a generally planarsurface. On either side of the upper planar surface of the valve seat502, are angled side surface that extend into contact with a lowerplanar surface thereby forming the conically shaped valve seat 502. Inthis embodiment, the pin 510 and ball 511 assembly contacts and sealsagainst the valve seat 502. In an alternate embodiment, such as thatshown in FIG. 5, the valve armature 224 contacts that valve seat 210.One purpose for shaping the seat in such a manner is to minimize flownoise during routine valve operation. Where the material surrounding theseating surface is angled away from the armature or pin, the contactarea is minimized thereby reducing the area over which flow forces canact. A seat shaped in this manner therefore tends to control of thevalve by minimizing Bernoulli effects (flow forces) acting on themovable parts of the valve. The reduction in flow forces diminishes thedeviation in the amount of magnetic force applied to the armature from aproscribed amount to maintain a proportional relationship between theforce applied and the distance traveled by the armature 524.Additionally, the use of the pin 510 acts to separate the magneticoperations in the upper part of the valve 500 from the hydraulicoperations in the lower part.

A fifth embodiment of a normally open control valve is indicatedgenerally at 500′ in FIG. 12. The control valve 500′ is substantiallysimilar to the valve shown in FIG. 9. In a preferred embodiment,however, the valve 500′ has a pin guide system 540. The pin guide system540 will allow the valve to maintain alignment of the pin 510 with thebore on the valve seat 502. The pin 510 is radially supported by the pinguide 540 at the lower end of the pin 510. This ensures that the ball511 is maintained in position over the valve opening in the valve seat502 despite hydraulic flow variation around the surface of the ball 511.Due to the constraints of the pin guide 540, the pin 510 can pivot onlyat the second ball 513 at the armature 524. In this embodiment it isalso preferred that the pin guide 540 engages the seat 502 as a separatepiece. Additionally, the adapter materials are selected for a goodmagnetic performance whereas the seat materials are generally selectedbased on durability and other performance traits.

In any of the embodiments described above, and particularly those shownin FIGS. 9 through 12, it is preferred that the upper part of thearmature 524 is centered and well-guided within the magnetic coil tominimize side loading and to maintain repeatable performance. This maybe accomplished with a close tolerance gap between the armature 524 andsleeve 525. The use of a low-friction material on the armature and otherelements further allows for ease of movement of those elements.Particularly, a low-friction coating such as “NIFLOR” can be used. Theuse of such a coating can also be used on the armature 524, pin 510 andother moving parts of the valve 500 and 500′.

Additionally, in the embodiments described and shown above in FIGS. 9through 12, the valve 500, 500′ has been shown as a normally-open valve.However, with minor adjustments, the valve can be used as anormally-closed valve. In particular, the spring 518 could be removedand another spring could be disposed between the stop 519 and theadapter 504. The spring could then bias the pin 510 and ball 511 towardsthe valve seat 502. Using the valve in a normally-open ornormally-closed position does not depart from the scope of the inventionin that the advantages of the valves 500 and 500′, such as the“double-step” or “triple-gap” design, still apply.

In a solenoid valve having a moving armature, there are two fundamentaltypes of flux gaps (air gaps). These are conventionally termed workingflux gaps and non-working flux gaps (see for example U.S. Pat. No.4,097,833 to Myers). Non-working flux gaps, as known in the art, areflux gaps in which the flux gaps between pole surfaces on a stator (e.g.pole piece) and pole surface on an armature have a substantiallyconstant reluctance over the range of motion of the armature. Workingflux gaps, as are also known in the art, are flux gaps for which thereis a substantial change in reluctance over the range of motion of thearmature. It will be readily apparent that the flux gaps 530 a, 532 a,and 530 b, and similar gaps discussed above, are working flux gaps.

There is illustrated in FIGS. 2–6, 8, 9, and 12, armatures havingdifferent configurations. Regardless, each armature is shown having amajor diameter. A major diameter is defined as the outer diameter. In anarmature having a non-uniform outer diameter, the major diameter is thelargest outer diameter of the armature. A flux gap that is formedexternal to the major diameter is a flux gap that extends beyond themajor diameter. A flux gap that is formed internal to the major diameteris a flux gap that is located substantially within the major diameter.

In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been explained andillustrated in its preferred embodiments. However, it must be understoodthat this invention may be practiced otherwise than as specificallyexplained and illustrated without departing from its spirit or scope.

1. A coil operated control valve comprising: a valve seat; a pole piecedefining at least a first pole shoulder and a second pole shoulder thatare both stationary relative to said valve seat; a coil for selectivelyinducing a magnetic flux in said pole piece; an armature moving a valveportion relative to said valve seat to control flow of a fluid throughsaid valve seat, said armature defining at least a first armatureshoulder and a second armature shoulder, said first armature shouldercooperating with said first pole shoulder to define a first lateral fluxgap and said second armature shoulder cooperating with said second poleshoulder to define a second lateral flux gap; and a closed tubestructure formed by a sleeve wherein said sleeve forms a pressureboundary about the armature, and the armature is disposed within saidsleeve, and said coil is disposed outside said sleeve.
 2. The controlvalve defined in claim 1 wherein said pole piece is fixed relative tosaid valve seat.
 3. The control valve defined in claim 2 wherein saidarmature moves a pin on which the valve portion is formed.
 4. Thecontrol valve defined in claim 3 wherein a lateral gap is formed by atubular flux ring having an inner diameter that is greater than a majorouter diameter of the armature.
 5. The control valve defined in claim 3wherein the first lateral flux gap is formed external to a major outerdiameter of the armature and the second lateral flux gap is formedinternal to the major outer diameter of the armature.
 6. The controlvalve defined in claim 1 further comprising an adapter wherein theclosed tube structure is sealed with the adapter; and the armaturecooperates with the adapter to allow the flow through the valve.
 7. Thecontrol valve defined in claim 6 wherein the sleeve is made from anon-magnetic material.
 8. The control valve defined in claim 4 whereinthe first lateral flux gap and the second lateral flux gap are locatedin a stepped relation to each other.
 9. The control valve defined inclaim 8 wherein the first lateral flux gap and the second lateral fluxgap are located at a circumferential radius that is less than that ofthe pole piece.
 10. The control valve defined in claim 1 wherein saidpole piece is disposed within said sleeve.
 11. A coil operated controlvalve comprising: a valve seat; a pole piece defining at least a firstpole shoulder and a second pole shoulder that are both stationaryrelative to said valve seat; an armature moving a valve portion relativeto said valve seat to control flow of a fluid through said valve seat,said armature defining at least a first armature shoulder and a secondarmature shoulder, said first armature shoulder cooperating with saidfirst pole shoulder to define a first working lateral flux gap and saidsecond armature shoulder cooperating with said second pole shoulder todefine a second working lateral flux gap; and a flux ring mounted abouta portion of said armature, a third working lateral flux gap beingdefined between a portion of said flux ring disposed about said armatureand the portion of said armature disposed in said flux ring.
 12. Thecontrol valve defined in claim 11 further comprising a pressurecontaining structure positioned between the flux ring and the armature.13. The control valve defined in claim 12 wherein the pressurecontaining structure is a non-magnetic sleeve; and the armature ispositioned within the sleeve.
 14. A coil operated control valvecomprising: a valve seat; a pole piece defining at least a first poleshoulder and a second pole shoulder that are both stationary relative tosaid valve seat; and an armature moving a valve portion relative to saidvalve seat to control flow of a fluid through said valve seat, saidarmature defining at least a first armature shoulder and a secondarmature shoulder, said first armature shoulder cooperating with saidfirst pole shoulder to define a first working lateral flux gap and saidsecond armature shoulder cooperating with said second pole shoulder todefine a second working lateral flux gap, wherein the first workinglateral flux gap is located adjacent to and in a stepped relationshipwith the second working lateral flux gap.
 15. The control valve definedin claim 14 wherein the first working lateral flux gap is formedexternal to a major outer diameter of the armature and the secondworking lateral flux gap is formed internal to the major outer diameterof the armature.